1. Field of the Invention
The present invention relates to a transmission device of driving-force for a camera, and in particular, to a transmission device of driving-force for a camera that transmits the driving-force of a driving source to various types of drive mechanisms provided inside the camera.
2. Description of the Related Art
Up to now, in regard to a means for transmitting the driving-force from a driving source such as a motor to various types of drive mechanisms such as a film feed mechanism and a lens drive mechanism, various proposals such as what are disclosed in Japanese Unexamined Patent Publication No. 8-304894 and Japanese Unexamined Patent Publication No. 6-347876 are performed and put to practical use.
In a camera disclosed in the Japanese Unexamined Patent Publication No. 8-304894, a transmission device of driving-force transmits the driving-force of a driving source such as a motor to respective drive mechanisms so as to make the camera perform winding operation or rewinding operation of a roll of film provided inside the camera, zooming operation of a picture-taking lens barrel, and the like with an arrangement of a plurality of spur gears and using a clutch mechanism skillfully devised.
In addition, a feed mechanism of a camera disclosed in the Japanese Unexamined Patent Publication No. 6-347876 transmits the driving-force of a driving source such as a motor to various types of drive mechanisms such as a spool shaft, winding the film through a spur gear engaging with a worm gear, and a fork feeding the film from a cartridge and rewinding the film into a cartridge.
Nevertheless, in a transmission device of driving-force in the camera disclosed in the Japanese Unexamined Patent Publication No. 8-304894, a gear train composed of a plurality of spur gears is used as a transmitting means of the driving-force. Although transmission means of driving-force using this type of gear train have been commonly used up to now, these means have such a problem that the number of spur gears increases if the transmission distance at the time of transmitting the driving-force is long. Therefore, in this case, its transmission efficiency is apt to decrease.
In addition, as disclosed in the Japanese Unexamined Patent Publication No. 8-304894, if the driving-force is transmitted from a single driving source to a plurality of drive mechanisms by switching the driving-force, the number of spur gears further increases due to construction of a plurality of transmission systems. Therefore, if this type of transmission device of driving-force is adopted in a small device such as a camera, a space for containing many gears becomes necessary, and hence the device itself becomes large in consequence. In addition, if respective gears constructing the transmission means are undersized so as to avoid this, there arises a problem that the number of the spur gears furthermore increases, and hence the transmission efficiency of the driving-force becomes worse.
On the other hand, according to the means disclosed in the Japanese Unexamined Patent Publication No. 6-347876, worm gears (an input gear and an output gear), provided in both ends of a drive shaft having a shape of a long shaft, and a shaft part are constructed with the shaft in one-piece. A transmission means of driving-force that has such construction has such a problem that it becomes a factor of hindering downsizing of a camera itself to strictly achieve the state of mutually engaging with respective gears in the input side that input the driving-force and the state of mutually engaging with respective gears in the output side that output the driving-force, because arrangement of the drive shaft inside the camera is restricted.